The death of a star disrupted its planetary system so “violently” that a white dwarf sucked in debris both in and out of the system. This is the first time astronomers have observed a white dwarf star consuming the rocky and metallic materials that make up planets.
A white dwarf is the remnant of a star (like the Sun) after it has shed its outer layers and stopped burning fuel through nuclear fusion.
Data released by NASA’s Hubble Space Telescope and other NASA observatories proved important in diagnosing this “cosmic cannibalism” case. The findings, based on analysis of material trapped in the atmosphere of the white dwarf star G238-44, help describe the “violent nature of planetary systems” and could give astronomers an understanding of the composition of the newly formed system.
“We’ve never seen both types of objects cluster together on a white dwarf at the same time,” said UCLA principal investigator and recent graduate Ted Johnson. In a statement released by NASA“By studying these white dwarfs, we hope to gain a better understanding of planetary systems that are still intact.”
The new survey is “surprising” given that small icy objects are thought to collide and “water” the dry, rocky planets in our solar system. “The composition of objects detected in white dwarfs suggests that icy reservoirs may be common in planetary systems,” Johnson explained.
“Life as we know it requires a rocky planet covered in elements such as carbon, nitrogen and oxygen,” said UCLA professor Benjamin Zuckerman. “What we see in this white dwarf star The abundance of elements seems to require both a rocky parent and a volatile-rich parent — the first example we have found in our study of hundreds of white dwarfs,” he added.
NASA explained that the theory of planetary system evolution describes the transition between the red giant and white dwarf phases as a “chaotic process.” The star “rapidly loses its outer layers” and the orbits of its planets “change dramatically.” The new study confirms “the true scale of this violently chaotic phase,” showing that 100 million years after the start of the white dwarf phase, the star is able to “capture and deplete material in both its asteroid belt and ribbon region at the same time.” Kuiper .
The results of this study suggest that “the total mass estimated to eventually be engulfed by the white dwarf may not exceed the mass of the asteroid or small moon”.
The team of scientists measured the presence of elements such as nitrogen, oxygen, magnesium, silicon and iron. The detection of large amounts of iron “is evidence for the metallic cores of terrestrial planets such as Earth, Venus, Mars and Mercury”. In addition, “the unexpectedly high nitrogen levels led scientists to conclude that ice bodies were present”.
“The best fit for our data is an almost two-to-one mixture of Mercury-like and comet-like material composed of ice and dust,” Johnson said. “The iron metal and nitrogen ice suggest that the conditions under which planets formed are very different. No known solar system object has such large amounts of both.”
When a star expands into a red giant at the end of its life, “it loses mass as the outer layers explode.” What are the consequences of doing so? “The gravitational scattering of any remaining large planets to small objects like asteroids, comets and moons,” NASA replied.
“After the red giant stage, the remaining white dwarfs are compact — no larger than Earth. These wayward planets end up very close to the star and experience strong tidal forces that pull them apart, forming a dusty gaseous disk. Eventually can fall to the surface of a white dwarf,” Johnson clarified.
The analysis of the elements detected in the white dwarf star, G238-44, took two years and was carried out by a team of researchers from the University of California and the University of Kiel in Germany.